This invention relates to the production of complementary insulated gate field effect transistors, hereinafter called IGFETs, on the same substrate.
It is known to provide a substrate of N-type semiconductive material and to provide a tube or region of P-type semiconductive material in the same semiconductive substrate. Then two separated P.sup.+ regions are put in the N substrate outside of the tub to act as a source and drain for a P-type IGFET, the channel being the substrate between the two P.sup.+ diffused regions. Furthermore, two separated N.sup.+ regions are put into the P.sup.- tub to act as source and drain of an N-type IGFET. The tub material between the last-mentioned source and drain forms the channel for the N-type IGFET. In such prior art complementary IGFETs, PN junctions occur between each source and drain and the material in which it is included for each of the two transistors, resulting in four PN junctions, A fifth PN junction is provided between the tub and the substrate. Several bipolar transistors are formed inherently between the various regions of opposite conductivity type. Two of the bipolar transistors in such a construction have elements in common whereby these two bipolar transistors can act as a silicon controlled rectifier, SCR, which can be triggered to prevent proper operation of the IGFETs. Furthermore, the material on each side of each of the several PN junctions are electrodes and the PN junction itself acts as a dielectric whereby several capacitors are inherently produced. The so-produced IGFETs operate slowly since, in the operation thereof, time is required for charging and discharging the several capacitors.
It is an object of this invention to provide complementary IGFETs in the same substrate that are so isolated that there is no danger of latch-up.
It is another object of this invention to provide complementary IGFETs in the same substrate that are faster-operating than presently known such IGFETs.
It is another object of this invention to provide complementary IGFETs on the same substrate that exhibit less capacity than known such IGFETs.